Incidence and case fatality rates for acute appendicitis in California. A population-based study of the effects of age.

In 1984, 24,794 appendectomies and abscess drainage procedures were performed for acute appendicitis in California hospitals. Analysis of hospital discharge abstracts revealed age- and sex-specific incidence rates and in-hospital case fatality rates for acute appendicitis lower than previously reported. In persons aged 60 years and older, the case fatality rate for nonperforating appendicitis with appendectomy was 0.7% and for perforating appendicitis and abscess 2.4%. Surgery was delayed beyond the day of admission in 21% of persons aged 40-59 years, 29% of persons aged 60-79 years, and 47% of persons aged 80 years and over. The proportion of cases with perforation increased from 22% to 75% between ages 20 and 80 years. The population incidence of perforating appendicitis changed little after age 20 years, while the incidence of nonperforating cases declined sharply. The high proportion of appendicitis cases with perforation among the elderly may be due to the decreased incidence of nonperforating appendicitis in the elderly and not to a greater propensity for perforation, as previously proposed. Most elderly in California receive timely surgery for appendicitis and tolerate it better than previously reported. Diminished tolerance for intra-abdominal infection may be the primary determinant of the increase in case fatality with age.